US4587470A - Multiplex control system - Google Patents

Multiplex control system Download PDF

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Publication number
US4587470A
US4587470A US06/661,948 US66194884A US4587470A US 4587470 A US4587470 A US 4587470A US 66194884 A US66194884 A US 66194884A US 4587470 A US4587470 A US 4587470A
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United States
Prior art keywords
controller
subsidiary
operator
main controller
control
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US06/661,948
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English (en)
Inventor
Masahiko Yamawaki
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Assigned to MITSUBISHI DENKI KABUSHIKI KAISHA, reassignment MITSUBISHI DENKI KABUSHIKI KAISHA, ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: YAMAWAKI, MASAHIKO
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B9/00—Safety arrangements
    • G05B9/02—Safety arrangements electric
    • G05B9/03—Safety arrangements electric with multiple-channel loop, i.e. redundant control systems

Definitions

  • the present invention relates to a multiplex control system including a main controller and a subsidiary controller with different control characteristics, the system being capable of getting rid of the output error between these controllers.
  • FIG. 1 shows, as an example of such multiplex control systems, the arrangement of a dual control system.
  • the system includes a process data input unit 10 receiving process data, e.g., pressure, temperature, flow rate, etc., from process lines (not shown), a main controller 11, a subsidiary controller 12, a data link unit 13, a switch unit 14, and a control object 15, e.g., valves.
  • process data collected on process lines (not shown) are received by the process data input unit 10 and delivered to the main controller 11 and subsidiary controller 12.
  • the main controller 11 performs computation based on the data and transmits the result through the data link 13 to the subsidiary controller 12.
  • a switch unit 14 operates to transfer control of the control object from the main controller 11 to the subsidiary controller 12.
  • the difference between the integral term of the analog PID operator in the main controller and the integral term of the subsidiary PID operator is added to the integral term provided by the digital PID operator of the subsidiary controller through the operator of time lag of first order, whereby the output error of the digital PID operator is cancelled and, when the difference between the output of the digital PID operator and the output of the analog PID operator has increased beyond a predetermined value, the switch unit performs switching of control in a bumpless fashion from the main controller to the subsidiary controller.
  • FIG. 1 is a block diagram of the conventional multiplex control system including controllers of the same control characteristics
  • FIG. 2 is a block diagram of the multiplex control system embodying the present invention.
  • component blocks 10 and 15 denote a process data input unit and a control object identical to those of the conventional system as mentioned previously.
  • the system further includes an analog PID operator (operational circuit) 21 provided within the main controller 11 and adapted to perform computation in response to the proportional component, integral component and differential component of process data fed from the process data input unit 10, a digital PID operator (operational circuit) 22 provided within the subsidiary controller 12 and adapted to perform the PID computation equivalent to that of the analog PID operator 21, an adder/subtracter 23 which calculates the difference, as control error, between the integral component of the output of the analog PID operator 21 and the integral component of the output of the digital PID operator 22, and a time lag operator 24 which provides a time lag of first order for the control error.
  • an analog PID operator operational circuit
  • 22 provided within the subsidiary controller 12 and adapted to perform the PID computation equivalent to that of the analog PID operator 21
  • an adder/subtracter 23 which calculates the difference, as control error, between the integral component of the output of
  • the analog PID operator 21 is achieved by hardware, while the digital PID operator 22, adder/subtracter 23 and time lag operator 24 are achieved by software. Further included in the system are an adder/subtracter 28 which calculates the difference, as output error, between the output of the digital PID operator 22 and the output of the analog PID operator 21 and operates on a switching signal generator 26 to activate a switch unit 25, and a first-order time lag element 27 used to prevent the analog PID operator 21 from tracking the open-circuited state when the relay in the switch unit 25 operates.
  • the switching signal generator 26 issues the switching signal to the switch unit 25 so that the control of the main controller is replaced by the control of the subsidiary controller.
  • the difference of control outputs of the main controller 11 and subsidiary controller 12 is prevented from diverging, and upon occurrence of abnormality in the main controller, the subsidiary controller can take control in a bumpless fashion without leaving a difference of outputs between these controllers.
  • the time lag operator 24 is invalidated so that it does not affect the control characteristics.
  • controllers with different control characteristics can be multiplexed, whereby an existing analog control system can readily be multiplexed for the enhancement of reliability and, at the same time, in the occurrence of abnormality of the main controller it can be replaced with the subsidiary controller in a bumpless fashion without the divergence of control output error.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Feedback Control In General (AREA)
  • Safety Devices In Control Systems (AREA)
US06/661,948 1983-10-18 1984-10-17 Multiplex control system Expired - Lifetime US4587470A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP58196576A JPS6086602A (ja) 1983-10-18 1983-10-18 多重化制御方式
JP58-196576 1983-10-18

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US4587470A true US4587470A (en) 1986-05-06

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US06/661,948 Expired - Lifetime US4587470A (en) 1983-10-18 1984-10-17 Multiplex control system

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JP (1) JPS6086602A (ja)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4679136A (en) * 1984-04-13 1987-07-07 Kabushiki Kaisha Toshiba Dynamic error compensating process controller
US4745541A (en) * 1986-06-16 1988-05-17 Cincinnati Milacron Inc. Method and apparatus for process control
US4874999A (en) * 1987-11-25 1989-10-17 Hitachi, Ltd. Automatic control system
US4882669A (en) * 1983-11-28 1989-11-21 Canon Kabushiki Kaisha Multi computer fail safe control apparatus
EP0424862A2 (de) * 1989-10-27 1991-05-02 Mtu Motoren- Und Turbinen-Union MàœNchen Gmbh Analoger Mehrkanalregler
US5093609A (en) * 1988-01-19 1992-03-03 Fanuc Ltd. Servomotor control method
US5210704A (en) * 1990-10-02 1993-05-11 Technology International Incorporated System for prognosis and diagnostics of failure and wearout monitoring and for prediction of life expectancy of helicopter gearboxes and other rotating equipment
US5229699A (en) * 1991-10-15 1993-07-20 Industrial Technology Research Institute Method and an apparatus for PID controller tuning
EP0615180A1 (de) * 1993-03-08 1994-09-14 Landis & Gyr Technology Innovation AG Elektrische Überwachungsanordnung
US5452200A (en) * 1993-10-20 1995-09-19 United Technologies Corporation Control system that selects proportional-integral control channels having integrator update capability
US5504672A (en) * 1993-09-10 1996-04-02 Hardiman; Ted L. Industrial process controller and method of process control
US6150786A (en) * 1997-11-26 2000-11-21 Fanuc Ltd. Controller for industrial machine
US20090281639A1 (en) * 2008-05-12 2009-11-12 Mcnab Keith George Method and system for process control configuration changes
DE102009002689B4 (de) * 2009-04-28 2013-07-11 Robert Bosch Gmbh Regelvorrichtung mit wenigstens zwei Reglern

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60251401A (ja) * 1984-05-28 1985-12-12 Yamato Scient Co Ltd 温度制御装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013877A (en) * 1974-08-13 1977-03-22 Westinghouse Electric Corporation Combined cycle electric power plant with a steam turbine having an improved valve control system
US4031372A (en) * 1973-11-06 1977-06-21 Westinghouse Electric Corporation System for manually or automatically transferring control between computers without power generation disturbance in an electric power plant or steam turbine operated by a multiple computer control system
US4209734A (en) * 1978-03-27 1980-06-24 Sperry Corporation Dynamic equalization system for dual channel automatic pilot
US4390942A (en) * 1979-10-19 1983-06-28 Ihc Holland N.V. Control system
JPS5920182A (ja) * 1982-07-23 1984-02-01 株式会社荘大商会 ゴルフクラブヘツド
US4504905A (en) * 1981-09-05 1985-03-12 Lucas Industries Plc Digital control system including means for maintaining signals supplied thereby within limiting values

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4031372A (en) * 1973-11-06 1977-06-21 Westinghouse Electric Corporation System for manually or automatically transferring control between computers without power generation disturbance in an electric power plant or steam turbine operated by a multiple computer control system
US4013877A (en) * 1974-08-13 1977-03-22 Westinghouse Electric Corporation Combined cycle electric power plant with a steam turbine having an improved valve control system
US4209734A (en) * 1978-03-27 1980-06-24 Sperry Corporation Dynamic equalization system for dual channel automatic pilot
US4390942A (en) * 1979-10-19 1983-06-28 Ihc Holland N.V. Control system
US4504905A (en) * 1981-09-05 1985-03-12 Lucas Industries Plc Digital control system including means for maintaining signals supplied thereby within limiting values
JPS5920182A (ja) * 1982-07-23 1984-02-01 株式会社荘大商会 ゴルフクラブヘツド

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4882669A (en) * 1983-11-28 1989-11-21 Canon Kabushiki Kaisha Multi computer fail safe control apparatus
US4679136A (en) * 1984-04-13 1987-07-07 Kabushiki Kaisha Toshiba Dynamic error compensating process controller
US4745541A (en) * 1986-06-16 1988-05-17 Cincinnati Milacron Inc. Method and apparatus for process control
US4874999A (en) * 1987-11-25 1989-10-17 Hitachi, Ltd. Automatic control system
US5093609A (en) * 1988-01-19 1992-03-03 Fanuc Ltd. Servomotor control method
EP0424862A2 (de) * 1989-10-27 1991-05-02 Mtu Motoren- Und Turbinen-Union MàœNchen Gmbh Analoger Mehrkanalregler
EP0424862A3 (en) * 1989-10-27 1991-10-16 Mtu Muenchen Gmbh Analogic multiple-channel controller
US5210704A (en) * 1990-10-02 1993-05-11 Technology International Incorporated System for prognosis and diagnostics of failure and wearout monitoring and for prediction of life expectancy of helicopter gearboxes and other rotating equipment
US5229699A (en) * 1991-10-15 1993-07-20 Industrial Technology Research Institute Method and an apparatus for PID controller tuning
US5619131A (en) * 1993-03-08 1997-04-08 Landis & Gyr Business Support Ag Parallel analog-digital monitoring system
EP0615180A1 (de) * 1993-03-08 1994-09-14 Landis & Gyr Technology Innovation AG Elektrische Überwachungsanordnung
US5504672A (en) * 1993-09-10 1996-04-02 Hardiman; Ted L. Industrial process controller and method of process control
US5452200A (en) * 1993-10-20 1995-09-19 United Technologies Corporation Control system that selects proportional-integral control channels having integrator update capability
US6150786A (en) * 1997-11-26 2000-11-21 Fanuc Ltd. Controller for industrial machine
US20090281639A1 (en) * 2008-05-12 2009-11-12 Mcnab Keith George Method and system for process control configuration changes
WO2009139990A1 (en) * 2008-05-12 2009-11-19 Ge Fanuc Intelligent Platforms, Inc. Method and system for a bumpless pid controller switch
CN102067047A (zh) * 2008-05-12 2011-05-18 通用电气智能平台有限公司 用于无扰动pid控制器切换的方法和系统
CN102067047B (zh) * 2008-05-12 2013-08-21 通用电气智能平台有限公司 用于无扰动pid控制器切换的方法和系统
US8718799B2 (en) * 2008-05-12 2014-05-06 Ge Fanuc Intelligent Platforms, Inc. Method and system for process control configuration changes
DE102009002689B4 (de) * 2009-04-28 2013-07-11 Robert Bosch Gmbh Regelvorrichtung mit wenigstens zwei Reglern

Also Published As

Publication number Publication date
JPS6086602A (ja) 1985-05-16

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